A transmission assembly of the structure set forth above is known from U.S. Pat. No. 5,058,455. In the transmission assembly shown in this U.S. patent, the bearing support frame is supported by the transmission casing by being secured to internal bosses which are projected inwardly from a front end portion of the transmission casing.
In an embodiment shown in the above-referenced U.S. patent, a fluid pump for supplying fluid to the fluid-operated first change mechanism is mounted on a front surface of the partition wall and is adapted to be driven by an input shaft of the fluid-operated change mechanism. No fluid supply passage means is provided within the vehicle body for supplying fluid from a fluid sump within the vehicle body to the fluid pump. It is thus considered that a fluid supply piping is arranged at an outside of the vehicle body. Such outside piping may often be an obstruction and will require a tight sealing for preventing oil leak perfectly. Accordingly, if fluid supply passage means could be arranged within the vehicle body successfully without any problem, that would be very advantageous.
Further, because a fluid-operated speed change mechanism comprises plural fluid-operated clutches having relatively large size and large weight, it is desirable to assemble this mechanism into a rear hall of the front housing fully in advance and then to install the front housing onto the front of the transmission casing. However, the bearing support frame set forth above does not allow such a previous full assembly with respect to the front housing because this support frame is designed as a member to be supported by the transmission casing.
An object of the present invention is to provide an improved transmission assembly for tractors in which fluid supply passage means for a fluid pump is fully arranged within a tractor vehicle body without causing any problem.
Another object of the present invention is to provide an improved transmission assembly for tractors in which a fluid-operated speed change mechanism is provided so as to assemble it into a rear half of a front housing in advance in a fully assembled condition while facilitating the arrangement of fluid supply passage means for a fluid pump within a tractor vehicle body.